Thin film transistors can be used as a switch member in display or touch sensitive areas. The thin film transistor generally includes a gate electrode on a substrate, an electrically insulating layer covering the gate electrode, a channel layer located on the electrically insulating layer, a source electrode and a drain electrode located on two sides of the channel layer respectively. The thin film transistor can further include an electric conduction layer between the channel layer and the electrically insulating layer. In manufacturing the thin film transistor, a plurality of masking steps of photolithographic processes are applied to form the channel layer and the electric conduction layer.